The Save: Paula's Choice Resist C15 Super Booster, $48

The Splurge:
SkinCeuticals C E Ferulic, $162

The Breakdown:
We reach for serums when we want a concentrated dose of nutrients. Usually a serum is one of the last products to touch your skin (after cleansing and toning), so according to Frey, it's worth shelling out slightly more for clinically proven ingredients.

In terms of pricing, it's helpful to think of serums as the wine of skin care, meaning, you can tell a difference between a $10 and a $50 bottle, but between $50 and $500, the difference is mostly reputation.

This SkinCeuticals tonic is packed with ferulic acid, which protects against photoaging (aka, wrinkles caused by the sun), as well as Vitamins C and E, which further fortify that barrier. With the price tag, you're paying for the high concentrations of these active ingredients.

For less than a third of the price, this Paula's Choice serum is quite similar, sporting nearly equal percentages of each antioxidant. The product even boasts the same distinctive, almost meaty scent of the SkinCeuticals. (Weird, we know.)

Though you can find even less expensive products at the drugstore (the "Two-Buck Chucks" of serums, if you will), that's when you start noticing a drastic change in ingredients and efficacy.

The Save: Proactiv+ Three-Step System, $29.95

The Splurge:
SkinMedica Acne System, $104

The Breakdown:
In the land of acne treatments, two ingredients reign supreme: benzoyl peroxide, which acts as an antiseptic, and salicylic acid, a chemical exfoliator. The former tends to work best on bacteria-laden whiteheads and the latter on blackheads and big, red blemishes. Used together, they combat all of the above.

SkinMedica's pricier kit contains a 2 percent salicylic acid cleanser and toner, as well as a 2.5 percent benzoyl peroxide moisturizer. The Proactive+ kit features a 2.5 percent benzoyl peroxide cleanser and pore treatment, plus a 0.5 percent salicylic acid moisturizer.

The ingredients are the same; it's the products and concentrations that differ. While SkinMedica focuses more on salicylic acid and Proactiv+ on benzoyl peroxide, both ingredients are proven effective. And according to Frey, when an ingredient's percentage is stated directly, it means that percentage is guaranteed for the life of the product. In other words, you can trust both kits won't expire on you.

Marketing-wise, Proactiv+ has geared its product more toward teens and young adults, and SkinMedica toward adult-acne sufferers. Thus, one possible difference in price. But when you break it down, effective ingredients work — and Proactiv+'s won't care how old you are, as long as you don't.

The Save: Simple Revitalizing Eye Roll-On, $10.99

The Splurge:
Do Not Age with Dr. Brandt Triple Peptide Eye Cream, $80

The Breakdown:
The point of eye cream is to keep your fast-aging under-eye area as moisturized as possible. The more hydrated it is, the tauter it will be, staying firm and wrinkle-free over time.

The good news is that you don't need expensive ingredients to keep your under-eyes effectively hydrated. However, peptide-loaded eye creams are having a major moment. Peptides help build up the skin's barrier, making it less prone to burning and redness. Problem is, they're one of the priciest components of skin-care products. If you have sensitive skin, you might choose to spring for a peptide-infused eye cream, such as this Dr. Brandt pick.

For sensitive skin sufferers on a budget, try this gentle pick from Simple. It's free of harsh dyes, perfumes and other irritants. Though it's not a thick, decadent cream like Dr. Brandt's, it contains derm-recommended elements, like de-puffing cucumber and hydrating glycerin, which get the job done for $70 less. Plus, the packaging is opaque and airtight — unlike the Dr. Brandt jar — meaning the active ingredients are better protected against degradation and bacteria.

The Save: Mario Badescu Skin Care Seaweed Night Cream, $22

The Splurge:
La Mer Crème De La Mer, $170

The Breakdown:
Both La Mer and Mario Badescu's products use undersea plant extracts to create rich, deeply moisturizing face creams. While La Mer's texture is thicker and its scent is a touch more spa-like, there are other factors accounting for the price.

"La Mer's custom-made jar is much more expensive than standard [packaging]," explains Anne Pouillot, Research and Development Director at Alchimie Forever. Beyond the posh exterior, regardless of what it costs to manufacture the product itself, "pricing La Mer under $50 does not match the brand's story or desired customer," Pouillot explains.

In other words, La Mer is meant to be a splurge, while Mario Badescu tells a different story. It's a suite at the Four Seasons versus a double bed at the Marriott. One might be fancier, but at the end of the day, you'll sleep fine in both.

The Save: Neutrogena Wave Sonic Spinning Power-Cleanser, $16.49

The Splurge:
Clarisonic Mia 2 Facial Sonic Cleansing 2-Speed Brush, $149

The Breakdown:
Sonic cleansing devices promise to deliver a deeper clean than you can achieve with your hands.

Clarisonic's Mia 2 is a two-speed device, which you can customize with interchangeable brush heads ($27 each) depending on your skin type. You charge the device, then squeeze your favorite cleanser or makeup remover onto the brush head and glide it in circular motions over your face. The result is clean, smooth skin that feels like it's been purged of makeup, oil and dirt.

Neutrogena's two-speed Sonic Wave is a smaller battery-powered device. Though you can't switch out the brush heads or apply your cleanser of choice, it comes with a package of cleansing pads. You stick them on the device and discard after each use, which keeps things nice and clean for those with acne-prone skin. After use, your skin feels clean and soft, as well.

The Clarisonic comes in 15 colors and is overall more customizable than the Wave. It's a high-end product that delivers top-notch results. But if your budget can't accommodate the price tag, Neutrogena's drugstore device is a solid alternative.